1. Field of the Invention
The present invention relates to a method for synthesizing carbon nanowires directly on the internal surface of a three-dimensional structure including a carbon structure and, more particularly, to a method for synthesizing carbon nanowires at high density on the surface of pores or gaps present in a structure, and a hierarchical structure synthesized by the method.
According to the present invention, it is possible to fill fine pores or gaps in a structure, which cause a reduction in mechanical properties or conductivity, with high-density carbon nanowires, thus significantly improving mechanical or electrical performance of a final product.
2. Description of the Related Art
Carbon nanowires are generally classified into carbon nanofibers and carbon nanotubes and can be synthesized by various methods. In order to be practically applied in various fields, the carbon nanowires should be assembled on the surface of a structure with various materials and shapes by a method such as synthesis, coating, etc.
In general, the method for assembling carbon nanowires on a macro-scale three-dimensional structure may be generally divided into a method for forming various types of solutions or pastes using carbon nanowire powder and coating the solutions or pastes on the surface of a desired structure and a method for synthesizing carbon nanowires directly on the surface of a structure.
The method for coating the carbon nanowires on the surface of the structure can maximize the adhesion with the surface of the structure, but the carbon nanowires may be mixed with other undesirable substances. In particular, in a three-dimensional structure having many pores or gaps therein, it is most likely that surface heterogeneity occurs due to agglomeration of nanoparticles caused by surface tension, thus making it difficult to obtain a uniform performance of the structure.
Meanwhile, a catalyst is generally used in the method for synthesizing carbon nanowires directly on the surface of the structure. For example, a solution containing a component that can act as a catalyst may be coated on the surface of a structure, followed by heat treatment to obtain nano-sized catalyst particles, or nanoparticles that can act as a catalyst may be coated directly on the surface of the structure.
However, according to the above conventional methods, in the case of the structure having many pores or gaps therein, such as a carbon composite material comprising carbon fibers, it is difficult to synthesize carbon nanowires at high density on the surface of pores or gaps, thus causing a reduction in mechanical properties or conductivity of a final product.